Fuel injection apparatus

ABSTRACT

A fuel injection apparatus for a multicylinder internal combustion engine comprising an integrated unit formed in two easily separable parts of which the first part comprises a drive shaft for connection to the engine, a fuel pump, a fuel-metering device and a distributing valve to distribute the metered fuel to the engine injectors, and the second part comprises control means responding to the operating conditions of the engine and a mechanical adjuster set by the control means, the attachment together of the two parts being such as to connect the adjuster to the metering device for adjustment of the latter in accordance with the operating conditions of the engine.

tlnited States Patent [72] Inventor John Kammerer Harding CharltonKings, England [2 I] Appl. No. 876,276 [22] Filed Nov. 13, 1969 [45]Patented Dec. 7, 1971 [73] Assignee Dowty Technical Development LimitedCheltenham, England [32] Priority Dec. 12, 1968 [3 3] Great Britain 1 l1 59,047/68 [54] FUEL INJECTION APPARATUS 2 Claims, 4 Drawing Figs. [52]11.8.0 ..l23/139AM,

[51] Int. Cl ..F02m 59/32 [50] Field of Search 123/1 19,

139, 139.11 A, 139.17, 139.18, 14OMC [5 6] References Cited UNlTEDSTATES PATENTS 2,876,755 3/1956 Gold et a1. 123/140 MC Primary Examiner-Laurence M. Goodridge Au0rneyYoung & Thompson ABSTRACT: A fuel injectionapparatus for a multicylinder internal combustion engine comprising anintegrated unit formed in two easily separable parts of which the firstpart comprises a drive shaft for connection to the engine, a fuel pump,a fuel-metering device and a distributing valve to distribute themetered fuel to the engine injectors, and the second part comprisescontrol means responding to the operating conditions of the engine and amechanical adjuster set by the control means, the attachment together ofthe two parts being such as to connect the adjuster to the meteringdevice for adjustment of the latter in accordance with the operatingconditions of the engine.

PATENTEDBEB (I971 3.625191 SHEET 1 or 2 IN V E N TO R Joy/v humus: MmwvaATTORNEYS FUEL INJECTION APPARATUS This invention relates to a fuelinjection apparatus for a multicylinder internal combustion engine andmore particularly although not exclusively it relates to such apparatusfor use with a multicylinder spark-ignition internal combustion engine.

In accordance with the present invention a fuel injection apparatus fora multicylinder internal combustion engine comprises an integrated unitformed in two easily separable parts of which the first part comprises adrive shaft for connection to the engine, a fuel pump, a fuel-meteringdevice and a distributing valve to distribute metered fuel to the engineinjectors, and the second part comprises control means responding to theoperating conditions of the engine and a mechanical adjuster set by thecontrol means, the attachment together of the two parts being such as toconnect the adjuster to the metering device for adjustment of the latterin accordance with the operating conditions of the engine. By thisinvention it is possible to provide a standard fuel pump andfuel-metering device and to attach to it a control means responding to adesired engine-operating condition or conditions. In this way the fuelinjection apparatus may be easily modified to obtain particular kinds ofengine operation such for example as large power output, moderate poweroutput with fuel economy, or a clean exhaust.

The fuel-metering device may comprise a free piston movable with anadjustable stroke and a commutating valve for feeding fuel from the pumpto cause alternate movements of the piston and for connecting fueldisplaced by the piston to the distributing valve.

The commutating valve and the distributing valve functions may beperformed by a single rotary valve connected to the drive shaft. e 1

The mechanical adjuster in the second part may comprise means to adjustone stop in the first part which determines the stroke of the piston.

The control means may be arranged to respond to any of a number ofengine operation conditions such as for example as engine inlet manifoldpressure, ambient air temperature and exhaust back pressure.

One embodiment of the invention will now be particularly described withreference to the accompanying drawings in which,

FIG. I is a circuit diagram of a fuel injection apparatus in accordancewith the invention,

FIG. 2 is a longitudinal cross section through the fuel injectionapparatus of FIG. I, and

FIGS. 3 and 4 are views of the face valve member surface and cooperatingstatic surface incorporated in FIG. 2.

These drawings are also used to illustrate the invention contained inour copending application No. 844,790.

Reference is made initially to FIG. I. The apparatus is intended for usewith a six-cylinder spark-ignition engine. Fuel is drawn from the fueltank 1 by an engine-driven gear pump 2 and its delivery pressure iscontrolled by a relief valve 3 which passes excess fuel back to the fueltank. A restrictor 4 in series with the relief valve 3 ensures that thedelivery pressure of the pump 2 will increase with increased enginespeed. The fuel delivered from the pump 2 is fed to either end of acylinder 5 containing a free piston 6 by means of a rotary commutatorvalve 7. Fuel displaced from the opposite end of cylinder 5 to that fedwith liquid is again fed through the rotary valve 7 to a distributorvalve 8 which delivers the fuel to the injectors associated with thecylinders of the engine in a regularly recurring sequence.

The travel of the free piston 6 is limited by two stops 9 and II. Thestop 9 is manually adjustable by lever I2 to provide a rich mixture forstarting. The stop 11 is restrained by a cam 13 which is moved by twoevacuated bellows l4 and 15. The bellows 14 is mounted in a casing andsubjected to engine inlet manifold pressure. The bellows I5 is enclosedin another casing and is subjected to engine exhaust back pressure inthe engine exhaust manifold. While FIG. 1 shows that both stops 9 and 11are adjustable it is within the scope of the invention for one of thestops to be fixed and for all adjustments to be effected on the otherstop.

The rotary valve 7 and distributor valve 8 are mechanically driven fromthe engine and the arrangement is such that for every two completerotations of the engine the free piston will move six times betweenstops 9 and II to displace six discrete quantities of fuel. Thedistributor valve 8 will direct these six discrete quantities of fuel incorrect sequence to the six injectors associated with the cylinders ofthe engine. The inlet manifold pressure in the engine will be determinedby the setting of the engine inlet throttle, the engine speed and alsoby the ambient atmospheric pressure. Principally the pressure isdetermined by the setting of the throttle which will then determine themovement applied from the bellows 14 to the cam 13. At the same time theexhaust back pressure acts in a contrary sense to reduce partially themovement given by bellows 14 to the cam 13. The principal function ofthe bellows I5 is to compensate for the characteristics of differentexhaust systems which might be operative on different engines fittedwith the illustrated injection system. It is normal that the injectorsfor the cylinders are arranged in the inlet manifold immediatelyadjacent to the cylinder inlet valves and the period over which theinjection of fuel lasts for any injector is preferably arranged tocoincide with the normal induction stroke of each engine piston in itscylinder. In the case of a four-or six-cylinder engine it can bearranged that the delivery of the gear pump 2 is continuously or almostcontinuously fed to one or other injector.

Reference is now made to FIGS. 2, 3 and 4 of the drawings. Thesedrawings show in practical detail the apparatus embodying the circuitarrangement of FIG. 1. The drive shaft 16 (FIG. 2) protrudes from theright-hand end of the apparatus and is driven at half engine speed by abevel drive from the distributor shaft of the engine, or alternativelyit may be driven by a toothed belt from the crank shaft or the camshaft. Within the body of the device the drive shaft is connected todrive the gear pump 2 which is normally arranged to pump fuel at a rateof about four times the maximum rate at which the engine normally usesfuel thereby providing an adequate excess of fuel for starting. The pump2 delivers its fuel into a chamber 17 within the device. The pumpdelivery pressure is controlled by a relief valve (not shown) in FIG. 2but arranged as described in FIG. I. The shaft extends to the valvechamber 17 where it is coupled to the rotaryvalve member 18 of a facevalve. The rotary member is loaded by spring 19 and also by fuel pumppressure to engage the static valve face 23 formed on the static member21. This static member is conveniently a part of a fixed casing of theapparatus. The cooperating surfaces 22 and 23 of the moving andstationary members of the face valve are shown by FIGS. 4 and 3respectively. The rotating valve member has seven ports opening into itsface 22. Six of these ports 24, 25, 26, 27, 28 and 29 lie on the samecomparatively small pitch circle and are equidistantly spaced from oneanother. The remaining port 31 is located on a larger pitch circle. Thethree ports 24, 26 and 28 pass completely through the member 18 andcommunicate with the chamber I7. All of the four ports 25, 27, 29 and 31extend only partially through the member 18 and are internally allconnected together by means of passages 32 within the member I8. Thestationary face 23 includes two diametrically opposed ports 33 and 34 onthe smaller pitch circle and six equally spaced ports 35, 36, 37, 38, 39and 41 on the larger pitch circle. The two inner ports 33 and 34 areconnected by internal passages to the two ends of the metering cylinder5. The ports 35 to 41 are individually connected to screw-threadedconnections 42 in the body of the device from which pipes extend to theinjectors in the engine inlet manifold adjacent to the engine inletvalves.

During rotation of the engine and of the drive shaft I6 the pump 2 willpump fuel at pressure into the valve chamber I7. The rotary valve by thecooperation of the ports 24 to 29 and 33 and 34 will feed fuelalternately to the ends of the metering cylinder 5 and will connect theliquid delivered from the metering cylinder 5 to the passage 32 in themember 18 which is then fed to the distributor portion of the valve fordistribution to the injectors. The ports on the smaller pitch circlei.e. the ports 24 to 29 and 33 and 34 together form the commutatingportion of the valve and the ports 31, 35 to 41 form the distributingportion of the valve.

The elements of FIG. 2 so far described are contained in the right-handpart of the apparatus indicated generally by reference numeral 51. Thispart terminates at a plane surface 52 extending at right angles to theaxis of the cylinder 5. The stop 11 is located centrally of the surface52. The left-hand unit 53 of the apparatus may be detachably secured bya plane surface 54 to the surface 52, the means being any conventionalmeans such as screw-threaded bolts 50. Within the part 53 the bellows 14is located in a chamber 44 connected through connection 45 to the inletmanifold of the engine. Also within the part 53 the bellows 15 islocated in a chamber 46 connected by connection 47 to the exhaustmanifold of the engine. The cam 13 is located in a chamber 55 which liesbetween chambers 44 and 46, this cam being formed on a rod 56 whichinterconnects the two bellows. Chamber 55 is vented to atmosphere. A camfollower 43 is slidably mounted in the part 53 so as to project from thesurface 54 and to be capable of engaging the stop 11 when the two parts51 and 53 are secured together. The cam follower 43 engages the cam 13and the movement of the cam by the two bellows will adjust the followerand the stop 11. For convenience a diaphragm 57 is clamped in positionbetween the two surfaces 52 and 54 so that any slight leakage of fuelfrom the end of cylinder 5 containing stop 11 may be collected and fedthrough the return connection back to the fuel tank.

The movement of the stop 11 will be proportional to intake manifoldabsolute pressure less a constant multiplied by exhaust manifoldabsolute pressure. The correct value of this constant depends on enginedesign, particularly compression ratio and the exhaust pressurecorrection of the fuel injection apparatus can be changed by changingthe effective area of the bellows 15. Small corrections can also be madeby changing the diameter of the rod 56 which connects the two bellows.

By leaving a small amount of gas in the bellows l4 and arranging thatsome air flows through the bellows chamber 44 to the inlet manifold itis also possible to correct for a change in intake air temperature.

The right-hand stop is adjustable by means of a rotary cam 45 connectedto an adjustable handle. For the position shown in FIG. 2, stop 9 allowsthe largest amount of movement of the free piston 6 and thus thegreatest displacement of fuel which corresponds to the fuel flowrequired for starting the engine. For normal running the cam 45 isrotated to a predetermined position to urge the stop 9 inwardly into thecylinder to limit the travel of the piston 6.

it is also within the scope of the invention that the stop 9 should befixed in position and that cam 45 or the equivalent should be includedwithin the part 53 so that all control adjustment is effected byadjustment of the stop 11.

The described fuel injection apparatus may provide very simply for thefeeding of fuel to a spark-ignition multicylinder internal combustionengine such that under substantially all conditions of operation acorrect mixture strength may be obtained depending on the performancerequired from the engine which may be for example either maximum poweroutput or alternatively maximum economy of operation. Conventionalcarburetor systems for supplying fuel to a spark-ignition engine cannotgive an accurately constant control of mixture strength, either to theindividual cylinders or to the overall flow of air to the engine.Conventional fuel injection systems overcome these defects but tend tobe complicated and not to correct fully for variations in operatingconditions of the engine. The described embodiment in FIG. 2 is simpleand compact and can be arranged to give accurate control of mixturestrength within the engine particularly by virtue of the fact thatcontrol of fuel is in accordance with the absolute values of pressure inthe engine inlet manifold and in the exhaust manifold. The describedembodiment of FIG. 2 provides the one basic part 51 of the apparatuscontaining the fuel pump, the fuel-metering device means and thefuel-distributing valve and the part 53 which may be easily substitutedcan be so made as to obtain the desired operation of the engine, be itmaximum power output or maximum economy of operation.

While the described invention is particularly intended for use with amulticylinder spark-ignition engine it is usable with minormodifications for supplying fuel to the injectors of a compressionignition engine. With such an engine the constancy of the mixturestrength is irrelevant but the combination of rotary face valve memberand free piston metering device forms a compact fuel injection unitusable with such an engine. Of course the injectors would operatedirectly into the engine cylinders and the timing of the fuel injectionwould be accurately controlled in accordance with normal compressionignition practice.

I claim:

1. Fuel injection apparatus for a multicylinder internal combustionengine, comprising an integrated unit formed in two separable parts,joinable together at plane attachment surfaces, of which the first partcomprises a drive shaft for connection to the engine, a gear pump forpumping fuel to pressure, a fuel pressure chamber receiving fuel atpressure from the pump, a rotary disc valve mounted in said chamber,injector connections for the cylinders of the engine, a meteringcylinder, a reciprocatory free piston located in the metering cylinder,a pair of stops in said cylinder determining limits of movement of thefree piston, one of said stops being adjustable and extending to thesaid plane attachment surface, and passage means interconnecting therotary disc valve with the metering cylinder and the injectorconnections so that, during rotation of the shaft, the valve commutatesfuel to the metering cylinder to reciprocate the piston between thestops and distributes fuel from the cylinder to the injectorconnections, and of which the second part includes a linearly moving cammounted for sliding movement parallel to said attachment surface, a camfollower slidably mounted for movement at right angles to saidattachment surface in engagement with said cam and also in engagementwith said adjustable stop when the two parts are secured together, afirst closed chamber, an evacuated bellows in said first closed chamber,means adapting said first closed chamber for connection to the inletmanifold of the engine and spring loading to hold the cam against thebellows whereby movement of the bellows following change in manifoldpressure is communicated to said cam and to the cam follower to adjustthe position of said adjustable stop.

2. A fuel injection apparatus as claimed in claim I, wherein said secondpart includes a second closed chamber for connection to the exhaustmanifold of the engine, a second evacuated bellows mounted in saidsecond chamber and spring loading arranged to urge the second bellowsagainst the cam to effect linear movement thereof in opposition to thefirst bellows movement.

1. Fuel injection apparatus for a multicylinder internal combustionengine, comprising an integrated unit formed in two separable parts,joinable together at plane attachment surfaces, of which the first partcomprises a drive shaft for connection to the engine, a gear pump forpumping fuel to pressure, a fuel pressure chamber receiving fuel atpressure from the pump, a rotary disc valve mounted in said chamber,injector connections for the cylinders of the engine, a meteringcylinder, a reciprocatory free piston located in the metering cylinder,a pair of stops in said cylinder determining limits of movement of thefree piston, one of said stops being adjustable and extending to thesaid plane attachment surface, and passage means interconnecting therotary disc valve with the metering cylinder and the injectorconnections so that, during rotation of the shaft, the valve coMmutatesfuel to the metering cylinder to reciprocate the piston between thestops and distributes fuel from the cylinder to the injectorconnections, and of which the second part includes a linearly moving cammounted for sliding movement parallel to said attachment surface, a camfollower slidably mounted for movement at right angles to saidattachment surface in engagement with said cam and also in engagementwith said adjustable stop when the two parts are secured together, afirst closed chamber, an evacuated bellows in said first closed chamber,means adapting said first closed chamber for connection to the inletmanifold of the engine and spring loading to hold the cam against thebellows whereby movement of the bellows following change in manifoldpressure is communicated to said cam and to the cam follower to adjustthe position of said adjustable stop.
 2. A fuel injection apparatus asclaimed in claim 1, wherein said second part includes a second closedchamber for connection to the exhaust manifold of the engine, a secondevacuated bellows mounted in said second chamber and spring loadingarranged to urge the second bellows against the cam to effect linearmovement thereof in opposition to the first bellows movement.